Moderation
I have teenagers, and I'm also in IT. My 15 yr old understands more than many 'IT' people.
At 3, I would suggest educational programming. I was an only child left in front of the TV, and I could read before kindergarten - but I didn't watch sports or action movies, I watched PBS and cartoons. I was also active and played outside - so this is the format that I've set for my kids. If they're playing games or watching TV 'too much', then I send them outside. Another thing that helps is having multiple children and a single device. Forcing them to share obviously helps them learn to share and learn to face disappointment and limits - but also forces them to do something else when they don't have access to that device.
And don't hover. The kid is 3 and can entertain himself. Let him go out in the backyard with some friends and climb some stuff without you there to catch him.
